John h



com (ema I page cette JOHN H. ROBSON, OF OVID, MICHIGAN.

Letters Patent No. 102,160, dated April 19, 1870.

IMPROVEMENT IN MACHINE FOR JOINTING- THE CLEARING-TEETH OFCIIROSSC'U'T-v sAWs.

The Schedule referred to in these Lettera Patent and making part of thesame.

fo all whom yit may concern:

Be it known that I, JOHN H. Robson, of Ovid, inI the county of Clintonand State of Michigan, have invented a new and useful Machine forDetermining the Proper Length of the` Hook or Clearing-Teeth ofOrosscut-Saws, and also to be used as a ille-guage when dressing saidteeth to a proper length; and I do hereby declare that the following isa full, clear, and

exact description of the construction and operation of the same,reference being had to the accompanying drawings making a part of thisspecification, in which- Figures 1 and 2 represent two piecesofcast-iron or other substance suitable for the purpose.

Figure 3 represents the two pieces above inentioned, attached to eachother by two screws, and in proper adjustment for use. v

vAt letter a, iig. 1, the metal is to be chilled or casehardened, so asto resist tbe action of theiile, should they come in contact.

Letters b b, g. 1, represent two niortises, through which the twoscrews, seen at c c, fig. 3, work, and which admit of g. 1 heilig raisedor lowered to a proper adjustment.

Letter c, iig. 2, shows the bottom of the gap dropped alittle below thethick portions of that figure, as seen von each side of the gap. This isto carry it below the range ,of the hle, the bottom of the gap, at a,iig. 1,

being the gauge which determines the proper length of the dealing-teeth.

'- Letters d d, fig. 2,l represent two holes passing through that piece,which are to be cut with a thread of the right proportion to receive thescrews e e, g.

3, which are also cut on that portion which passes through fig. 2. Theupper halt ot'g. 2, on each side of the gap, is enough thicker than thelower half to admit the teeth-edge of the saw to pass up between figs. 1and 2 as far as these projections on iig. 2, and

so that a tooth, if longer than those on each side of it, will appearabove the bottoni of the gap, at a, fig.-

1, showing that it should be cut down to the line ataV to make it of aproper length.

To use this machine, fasten the saw Iwhich is to be led in a vise orother fastening, with the teeth up. Then let the operator take thismachine, and, with tig. 1 toward him and the gap between the mortises bb, tig. 1, upward, then insert the upper edge lof the saw in the openingg, tig. 3, and pass the machine down until the teeth of the saw rest onthe projection seen .at f f, ig.'2, andtry the teeth by passing themachine along the edge of the saw. If a clearing-tooth .appears abovethe bottom of the. gap at a, tig. 1, cut

Witnesses:

A, B. Woon, Jr., J. Q. PATTERSON.

